Sheet properties of Douglas fir kraft pulp after selective treatments of different fibre length fractions with cellulases

In an attempt to enhance the in-plane strength of handsheets produced from Douglas fir kraft pulp while limiting yield loss, the long fibre length fra ctions were independently treated with cellulase enzymes prior to recombina tion with the untreated short fibre length fractions. Employing this combin ed physical separation/enzymatic approach resulted in improvements in both burst and tensile indices by as much as 35% and 25%, respectively ol er the corresponding untreated controls. Additionally, significant improvements i n sheet density and smoothness were also obtained without subsequent refini ng. Modifications in handsheet properties could be maintained wizen enzymat ic treatments were followed by various degrees of refining, with the additi onal advantage that lower amounts of enzyme were required.